Electrical connector for refractory electrodes

ABSTRACT

An electrical connector adapted to be secured to an exposed-toatmosphere electrode end portion, with the connector in turn being adapted to urge one end of an electrical contact means into engagement with the electrode end face. The connector includes retainer means, pressure equalization means and resilient urging means, with the pressure equalization means and the one end of the electrical contact means substantially completely covering the electrode end face.

United States Patent Can [4 1 Aug. 1,1972

[54] ELECTRICAL CONNECTOR FOR REFRACTORY ELECTRODES [72] Inventor:

[73] Assignee: Corning Glass Works, Corning,

[22] Filed: Sept. 20, I971 [21] Appl. No.1 181,950

Yilmaz Can, Watertown, Mass.

[52] US. Cl ..l3/6, l3/l6, 339/263 R [51] Int. Cl. ..C03b 5/02, H05b 3/06 [58] Field of Search ..l3/6, 14, 15, 16, 17;

339/263 R, 263 E, 263 L; 200/158, 170 A [56] References Cited UNITED STATES PATENTS 3,249,675 5/1966 Matchen ..l3/l6X 3,530,222 9/1970 Raddatz ..l3/l6 3,584,510 6/1971 Harris ..339/263R Primary Examiner-Roy N. Envall, Jr. Attorney-Clarence R. Patty, Jr. and Ernst H. Ruf

[ 5 7 ABSTRACT An electrical connector adapted to be secured to an exposed-to-atmosphere electrode end portion, with the connector in turn being adapted to urge one end of an electrical contact means into engagement with the electrode end face. The connector includes retainer means, pressure equalization means and resilient urging means, with the pressure equalization means and the one end of the electrical contact means substantially completely covering the electrode end face.

9 Claims, 5 Drawing Figures PATENTEI] nus 1 m2 3581.506 sum 10!:

(PRIOR ART) INVENTOR. Yi/maz Can M AQQ ATTORNEY ELECTRICAL CONNECTOR FOR REFRACTORY ELECTRODES BACKGROUND OF THE INVENTION The field to which this invention pertains is that of electrical connectors for refractory electrodes, and more particularly to electrical connectors between the electrical power source and the exposed-to-atmosphere ends of the type of refractory electrodes that are used in electric melting furnaces.

The novel electrode connector of this invention may be used, for example, in connection with the melting of thermoplastic materials in a furnace of the type shown and described in US. Pat. No. 3,524,206 to Boettner et al. (also assigned to the assignee of this invention), although not restricted thereto.

Past methods of "clamping" refractory electrodes have most generally utilized conventional jaw-electrode terminal clamps that are attached to the exposedto-atmosphere electrode ends. In order to achieve successful clamping the outer electrode end must extend a substantial distance beyond the outer surface of the furnace side or bottom wall, thus even further increasing the cost of the already expensive refractory electrodes. In addition, due to having only spot connections, namely through the clamp jaws, the electrical contact areas were small and the current distribution was not uniform resulting in thermal stresses that led to electrode cracking.

SUMMARY OF THE INVENTION This invention solves the previously mentioned problems by allowing an electrical connection to be made that does not require that the electrode protrude beyond the outer surface of the furnace side and/or bottom wall. In addition, since the electrode connector essentially completely covers the electrode outer end face, it permits substantially even current distribution and subsequent substantially even heat distribution within the electrode.

In summary, this invention relates to an electrode connector adapted to be secured to an exposed end portion of a refractory electrode and which in turn urges one end of an electrical contact means into contact with the end face of the electrode end portion.

The electrode connector includes retainer means having an outer portion that is exposed and an inner portion that extends into and is fixedly secured within a bore in the exposed end portion of the electrode, pressure equalization means secured on the retainer means and adapted to have the one end of the electrical contact means interposed therebetween and the end face of the electrode end portion, and means for resiliently urging the pressure equalization means and consequently the contact means into contact with the end face of the exposed electrode end portion. The pressure equalization means and the one end of the contact means substantially completely cover the electrode end face, thereby permitting substantially even current distribution and subsequent substantially even heat distribution within the electrode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical cross-sectional view of an electrode installation in operative position in the side wall of a glass furnace and illustrates a prior art electrical connector assembly attached to the exposed end of the electrode.

FIG. 2 is an end view of the novel electrode connector of this invention.

FIG. 3 is a sectional view taken along line 33 of FIG. 2.

FIG. 4 is a cross-sectional view similar to that of FIG. 1 and shows the approximate electric current and voltage distribution paths in the electrode having attached thereto the prior art electrical connector assembly of FIG. 1.

FIG. 5 is a cross-sectional view similar to that of FIG. 3 and shows the approximate electric current and voltage distribution paths in the novel electrode connector of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, FIG. 1 illustrates an electrode connector assembly known in the prior art. There is disclosed one of either the side or bottom wall 10 of a furnace or refractory material, and a pool of molten material 12, glass for example, supported and/or contained by wall 10. lntegrally formed in wall 10 is an electrode-receiving post or aperture 14 having cross-sectional dimensions substantially equivalent to those of an electrode 16, whereby the latter may be complementally and quite snugly inserted within aperture 14.

Electrode 16 is a refractory electrode, preferably of a ceramic material such as tired tin oxide, and generally has an inner end portion either flush with the inner surface 18 of wall 10 or extending slightly into molten material 12. The outer end portion 17 of electrode 16 extends outwardly a substantial distance, for example about 4 inches, beyond the outer surface 20 of wall 10. Electrode outer end portion 17 is necessary in order to provide an attachment portion for the jaw or feet portions 24 of the conventional jaw-type electrode terminal clamp 22. Interposed between clamp jaw portions 24 and electrode outer end portion 17 is one end of a metal contact member 25 having its other end connected to an electric supply (not shown).

The novel electrode terminal clamp connector assembly of this invention is shown in FIGS. 2 and 3. An electrode 26, substantially similar in cross-sectional dimensions and material composition to electrode 16 has an inner or first end portion or molten material contact face, 28 either flush with wall inner surface 18 or extending slightly into molten glass 12. The outer or second end portion, or exposed face, 30 of electrode 26 may be essentially flush or co-planar with wall outer surface 20, extend slightly therebeyond, or be slightly recessed.

Electrode 26 has a centrally located first or blind bore 32 starting at outer end face 30 and extending toward inner end face 28. A second or through bore 34 is normal to and intersects first bore 32. Freely extending a substantial distance into first bore 32, is inner end portion 38 of retainer means 36, with the former having a through-bore 40 normal to the longitudinal axis of retainer means 36. Retainer means bore 40 is adapted to be coaxial with electrode second bore 34 and upon their alignment allows the insertion of pin or anchoring means 42 thereby effectively anchoring retainer means 36 to electrode. It should be noted that neither the end surface nor the outer surface electrode inner end portions are in binding contact with the surfaces of bore 32.

Extending outwardly and away from bore 32 and normal to electrode outer end face 30, is outer end portion 44 of retainer means 36, with portion 44 having at least a part thereof threaded as at 46.

Slidingly secured or journalled on retainer means outer end portion 44 is a pressure distribution plate or equalization means 47 generally in the form of a flat metal washer having a central aperture 50. Pressure plate 47 is adapted to substantially completely cover electrode outer end surface 30.

A metal contact member or means 52 is adapted to have a first end (not shown) connected to a source of electric power (not shown) and a second end or portion 54, having central aperture 56, is interposed between the inner surface 48 of pressure plate 47 and electrode outer end face 30. It should be noted that contact member second end portion 54 is also adapted to substantially completely cover electrode outer end surface 30. Contact member 52 is preferably composed of one or more layers of a flexible, generally woven mesh, metal strap, such as aluminum or silver.

Also slidingly secured or journalled on retainer means outer end portion 44 is a resilient urging means 60 generally in the form of a spring, such as a leaf spring having a central aperture 62. The spring outer end portions 64 bear against the outer surface of pressure plate 47, while the spring outer center portion 66 bears against an adjusting or fastening means 68 such as a nut threaded secured on threaded post 46 of retainer means outer end portion 44. If desired, a metal washer 72 may be interposed between spring portion 66 and nut 68. Depending upon the direction of turning of nut 68, spring 60 is either tightened or loosened, thus effectively allowing control of the amount of force pushing against pressure distribution plate 47.

Pressure distribution plate 47, by reason of its area similarity to both electrode outer end face 30 and contact means second end portion 54, provides a much more uniform pressure and electric current distribution on electrode end face 30 than clamp jaws 24 provide on outer end portion 17 of electrode 16 (shown in FIG. 1). This is of great importance in relation to refractory electrodes such as tin oxide electrodes which are stronger in compression than in tension. As can be seen in the prior art arrangement shown in FIG. 1, the known jaw-type electrode terminal clamp 22 requires that outer electrode portion 17 extend beyond furnace wall outer surface 20. This sets up a moment arm corresponding approximately to that portion of electrode outer end 17 corresponding to the distance L between the centerline through clamp jaw portion 24 and wall outer surface 20.

In addition to moment arm L, it must be recognized that with prior art jaw-type electrode terminal clamp 22 electrical contact is made with electrode 16 only in two spots, namely through clamp jaws 24. In comparison, with electrode connector 74 of this invention, basically comprised of retainer 36, pressure equalization means 47 and resilient urging means 60, when used as electrode connector assembly 76, (i.e. electrode connector 24 and contact means 52) electrical contact is made with nearly the entire end face 30 of electrode 26.

For example, when using electrodes 16 and 26 of equal cross-sectional dimensions, i.e., 2 inches by 4 inches, prior art electrode connector 22 has 4.15 inches of electrical contact area while novel electrode connector assembly 76 has 3.75x1.s7s memo-( 3 inches =7.040.37=6.64 inches of electrical contact area. Therefore, for the same amount of electrical current, the voltage drop at the contacts (PR) will be smaller for novel electrode connector 74 than for prior art electrode connector 22.

FIG. 4 is a schematic showing of the approximate electric current and voltage distribution paths in electrode l6 utilizing prior art connector 22 shown in FIG. 1. FIG. 5 is similar to FIG. 4 but is a showing of the approximate electric current and voltage distribution paths in electrode 26 having attached thereto novel connector 74 (not shown here but fully shown in FIGS. 2 and 3). The generally vertical lines 78 and 79 typically represent the voltage or iso-potential lines in electrodes l6 and 26 respectively, while generally horizontal lines 80, 81 typically represent the iso-current lines in electrodes 16 and 26, respectively. It should be noted that iso-current lines 80 in electrode 16 have initial generally arcuate paths extending from contact member 25 to about the iso-potential line 78, which cause further voltage drop in comparison with electrode 26. On the other hand, iso-current lines 81, extending from contact member 52 in contact with novel connector 74, have generally straight-line paths.

It should further be noted that the zones 84 created between every two adjacent iso-potential and iso-current lines 79 and 81 respectively, in FIG. 5 are of substantially equal size. In contrast thereto, the zones created between every two adjacent iso-potential and iso-current lines 78 and 80 respectively, in FIG. 4 vary extensively in size between those denominated as 86 to those denominated as 88.

Since the heat generated by the Joule effect is equal to volts amperes, each zone 84 will have the same amount of heat released, assuming the resistance of the electrode material is equal throughout. Therefore, the smaller the zone, such as 86, the hotter it will get, resulting in uneven temperature distribution.

One of the main problems with the use of prior art electrode connector 22 is premature electrode breakage as a result of cracking between clamp jaws 24 and wall 20, due to thermal stresses. Sudden increases in current flow during normal furnace operation produce sudden increases in electrode temperature especially in the area of the connector portion. This condition, which is further adversely affected by moment arm L (FIG. I), generally occurs within a generally vertical zone A (FIG. I) in electrode outer end portion 17 just beyond furnace wall outer surface 20.

The electrode connector 74 of this invention replaces conventional clamp connector 22 and thereby either eliminates or at least minimizes not only the projection and unnecessary cost of the refractory electrodes extending excessively beyond the outer surface of the furnace wall, thus reducing the deleterious moment arm, but also provides more electrical contact area and thus a smaller voltage drop, as well as much more uniform current distribution.

The various components of the novel electrode connector of this invention, such as retainer means 36, anchoring means 42, equalization means 47, resilient urging means 60, nut 68 and washer 72 are preferably made from a high temperature and creep resistant stainless steel alloy.

Equalization means 47 provides a substantially uniform pressure on contact means second end portion 54, with resilient urging means 60 loading plate 47 when the former is compressed and compensating for the linear expansion difference between pinned retainer means 36 and tin oxide electrode 26 as well as maintaining a necessary amount of pressure on contact portion 54 of elevated temperature and compensates for any creep of retainer means 36.

Although reference has been made to tin oxide electrodes, the novel electrode connector of this invention may be used on any refractory electrode, with the electrode cross-sectional shape not being restricted to any one shape. It should be noted however that equalization means 47 and contact means second end portion 54 should preferably be of similar cross-sectional shape and size, as the electrode, so as to substantially cover the outer end face of the electrode.

In order to achieve a similar goal, some of the electrode connector components may of course be modified. For example, retainer means 36 may be cemented in bore 32, with bore retainer means 36 and the cement preferably having the same coefficient of thermal expansion. Resilient urging means 60, in addition to comprising a leaf spring, may also be comprised of a Bellville spring or, (if washer 72 if of a larger radial dimension) a coil spring. In addition, threaded portion 46 of retainer means 36 may be replaced by a series of small apertures which are adapted to receive a pin, thereby replacing nut 68.

While the invention has been described in connection with possible forms or embodiments thereof, it is to be understood that the present disclosure is illustrative rather than restrictive and that further changes or modifications may be resorted to without departing from the spirit of invention or scope of the claims which follow.

What is claimed is:

l. A refractory electrode assembly for use in the electric heating of a molten mass comprising:

a. a refractory electrode adapted to have a first end portion thereof contacting the molten mass and a second end portion that is exposed to atmosphere, with said electrode having a first bore in said second end portion thereof and extending toward said first end portion; and

b. an electrical connector assembly attached to said electrode with said connector assembly comprisb,. retainer means having an inner end portion extending into said electrode first bore and an outer end portion that is exposed,

b,. means for anchoring said retainer means to said electrode;

b,. a substantially flat metal washer journalled on said retainer means outer end portion;

b.. a metal contact member adapted to have a first portion connected to an electric supply and a second portion interposed between said flat metal washer and the end face of said electrode second end portion;

b means for resiliently urging said flat washer and said contact member second portion against the end face of said electrode second end portion; and

b,. means for securing said resilient means, with said metal washer and said contact member second portion essentially completely covering the end face of said electrode second end portion thereby allowing substantially even current distribution within said electrode.

2. The electrode assembly of claim 1 wherein:

a. said refractory electrode is comprised of ceramic material, and

b. said resilient urging means comprises a leaf spring.

3. The electrode assembly of claim 1 wherein:

a. said refractory electrode is comprised of fired tin oxide; and

b. the end face of said electrode second end portion is substantially rectangular.

4. In combination with a furnace for electrically heating molten materials having vitrescent properties:

a. a refractory wall having an aperture extending between the outer and the inner surface thereof;

b. a refractory electrode fitting closely within said aperture and having a first body portion, in the vicinity of said inner wall surface, immersible in said molten material and a second body portion, in the vicinity of said outer wall surface, said electrode having a first bore in said second body portion thereof and extending toward said first body portion;

c. retainer means having an inner end portion extending into said electrode first bore and an outer end portion extending away from said first bore;

d. means for anchoring said retainer means to said electrode;

. a pressure distribution plate slidably secured on said retainer means outer end portion;

f. a metal contact member having a first portion adapted to be connected to an electric source and a second portion interposed between said pressure distribution plate and the end face of said electrode second body portion; and

. means for resiliently urging said pressure distribution plate and consequently said contact member second portion into abutment with the end face of said electrode second end portion, said pressure distribution plate and said contact member second portion substantially completely covering said electrode end face, thereby permitting substantially even current and subsequent even heat distribution within said electrode.

. The combination of claim 4 wherein:

said electrode has a second bore that intersects and is normal to said first bore;

. said retainer means inner end portion has a bore adapted to be coaxial with said electrode second bore; and

. said anchoring means comprises a pin member passing through said electrode second bore and the bore of said retainer means, thereby anchoring said retainer means to said electrode.

6. The combination of claim 4 wherein:

a. said refractory wall comprises a side wall and/or bottom wall of said furnace;

b. said refractory electrode is comprised of ceramic material; and

c. the end face of said electrode second body portion is essentially coplanar with the outer wall surface of said refractory wall.

7. The combination of claim 4 wherein:

a. said resilient urging means comprises a leaf spring;

b. said pressure distribution plate comprises a substantially flat, centrally apertured washer;

c. said metal contact member comprises a flexible silver strap, and

d. the end face of said electrode second body portion is parallel with the outer wall surface of said refractory wall.

8. The combination of claim 6 wherein:

a. the end face of said electrode second body portion is substantially rectangular; and

b. said refractory electrode is comprised of fired tin oxide.

9. An electrode connector assembly fixedly attached to and abutting the end face, that is exposed to atmosphere, of a refractory electrode used in electric melting operations, said assembly comprising:

a. retainer means having a first portion fixedly secured to said electrode and a second portion extending therefrom normal to said electrode outer end face;

b. a pressure distribution means journalled on said retainer means second portion and essentially completely covering said electrode end face;

c. contact means having a first portion adapted to be connected to power supply means and a second portion fitted between said pressure distribution means and said electrode outer end face and essentially completely covering said electrode end face; and

d. adjustable resilient urging means, secured with respect to said retainer means second portion, for urging said pressure distribution means and consequently said contact means second portion into touching, resilient abutment with said electrode end face, thereby allowing substantially even current distribution within said electrode. 

1. A refractory electrode assembly for use in the electric heating of a molten mass comprising: a. a refractory electrode adapted to have a first end portion thereof contacting the molten mass and a second end portion that is exposed to atmosphere, with said electrode having a first bore in said second end portion thereof and extending toward said first end portion; and b. an electrical connector assembly attached to said electrode with said connector assembly comprising: b1. retainer means having an inner end portion extending into said electrode first bore and an outer end portion that is exposed, b2. means for anchoring said retainer means to said electrode; b3. a substantially flat metal washer journalled on said retainer means outer end portion; b4. a metal contact member adapted to have a first portion connected to an electric supply and a second portion interposed between said flat metal washer and the end face of said electrode second end portion; b5. means for resiliently urging said flat washer and said contact member second portion against the end face of said electrode second end portion; and b6. means for securing said resilient means, with said metal washer and said contact member second portion essentially completely covering the end face of said electrode second end portion thereby allowing substantially even current distribution within said electrode.
 2. The electrode assembly of claim 1 wherein: a. said refractory electrode is comprised of ceramic material, and b. said resilient urging means comprises a leaf spring.
 3. The electrode assembly of claim 1 wherein: a. said refractory electrode is comprised of fired tin oxide; and b. the end face of said electrode second end portion is substantially rectangular.
 4. In combination with a furnace for electrically heating molten materials having vitrescent properties: a. a refractory wall having an aperture extending between the outer and the inner surface thereof; b. a refractory electrode fitting closely within said aperture and having a first body portion, in the vicinity of said inner wall surface, immersible in said molten material and a second body portion, in the vicinity of said outer wall surface, said electrode having a first bore in said second body portion thereof and extending toward said first body portion; c. retainer means having an inner end portion extending into said electrode first bore and an outer end portion extending away from said first bore; d. means for anchoring said retainer means to said electrode; e. a pressure distribution plate slidably secured on said retainer means outer end portion; f. a metal contact member having a first portion adapted to be connected to an electric source and a second portion interposed between said pressure distribution plate and the end face of said electrode second body portion; and g. means for resiliently urging said pressure distribution plate and consequently said contact member second portion into abutment with the end face of said electrode second end portion, said pressure distribution plate and said contact member second portion substantially completely covering said electrode end face, thereby permitting substantially even current and subsequent even heat distribution within said electrode.
 5. The combination of claim 4 wherein: a. said electrode has a second bore that intersects and is normal to said first bore; b. said retainer means inner end portion has a bore adapted to be coaxial with said electrode second bore; and c. said anchoring means comprises a pin member passing through said electrode second bore and the bore of said retainer means, thereby anchoring said retainer means to said electrode.
 6. The combination of claim 4 wherein: a. said refractory wall comprises a side wall and/or bottom wall of said furnace; b. said refractory electrode is comprised of ceramic material; and c. the end face of said electrode second body portion is essentially coplanar with the outer wall surface of said refractory wall.
 7. The combination of claim 4 wherein: a. said resilient urging means comprises a leaf spring; b. said pressure distribution plate comprises a substantially flat, centrally apertured washer; c. said metal contact member comprises a flexible silver strap, and d. the end face of said electrode second body portion is parallel with the outer wall surface of said refractory wall.
 8. The combination of claim 6 wherein: a. the end face of said electrode second body portion is substantially rectangular; and b. said refractory electrode is comprised of fired tin oxide.
 9. An electrode connector assembly fixedly attached to and abutting the end face, that is exposed to atmosphere, of a refractory electrode used in electric melting operations, said assembly comprising: a. retainer means having a first portion fixedly secured to said electrode and a second portion extending therefrom normal to said electrode outer end face; b. a pressure distribution means journalled on said retainer means second portion and essentially completely covering said electrode end face; c. contact means having a first portion adapted to be connected to power supply means and a second portion fitted between said pressure distribution means and said electrode outer end face and essentially completely covering said electrode end face; and d. adjustable resilient urging means, secured with respect to said retainer means second portion, for urging said pressure distribution means and consequently said contact means second portion into touching, resilient abutment with said electrode end face, thereby allowing substantially even current distribution within said electrode. 